In 1987 Kröger started his academic career as research associate at Cologne's Department of Phonetics, which was then headed by Georg Heike. He became assistant professor in Cologne in 1990, and was guest professor at Berlin's Humboldt University in 1999. Since 2001 he has been professor and senior researcher at the Department of Phoniatrics, Pedaudiology and Communication Disorders, Medical School, RWTH Aachen University. He has been guest professor at Tianjin University, China since 2011.[3]